Hi Woody.

If I'm going to square rule to half-inch under, I just draw the timbers at half-inch under, and not try to draw all the reductions, I know what they look like, and I just figure that out in the shop.

In your design you are making a common mistake made by stick framers who are new to TF design: Crowding too much joinery into a single point. And you haven't even added the hardest part yet, which is the valley rafter itself! I strongly advise you to spread things out so that you get saner joinery. For example, would you be willing to take that gable end on the left of your drawing, and pull it toward you by a foot? I realize that it would break up the wall facing the camera, but it would "spread out" the joinery somewhat. You could also drop the tie beam on that gable end. With the two posts in "queen" position, it's really not acting much like a truss.

Regarding beam sizes, you'll need an engineer to do the math for you. There are no tables you can look up in timber framing. Things that will matter: wood species, snow load, roof pitch, and spans. CB.

Clark Bremer
Proud Member of the TFG